# TE optimization for J‐difference editing of 2‐hydroxyglutarate at 3T

## TL;DR

This study finds that a TE of 90 ms optimizes the detection of 2-hydroxyglutarate in brain tumors while minimizing interference from other signals.

## Contribution

The paper introduces an optimized TE protocol for J-difference editing of 2HG in MRS, validated through simulations and in vivo data.

## Key findings

- A TE of 90 ms maximized 2HG signal and reduced overlap with Glx compared to 70 ms.
- In vivo T2 relaxation times for 2HG, Glx, and water were measured as 264, 177, and 110 ms, respectively.
- Fit quality improved by 49% at 90 ms TE, indicating better spectral resolution.

## Abstract

To investigate the TE dependence of the edited 2‐hydroxyglutarate (2HG) signal, its separation from co‐edited glutamate plus glutamine (Glx), and fit accuracy in the presence of nuisance signals using a MEGA‐PRESS sequence.

Simulations were performed at TEs 70–160 ms to assess the signal intensity and 2HG‐Glx overlap as a function of TE. The effect of the 2HG‐Glx spectral overlap on the fit accuracy of 2HG was evaluated on simulated 2HG‐edited spectra with in vivo parameter variations. Data were acquired at TEs of 70 and 90 ms in 13 glioma patients to estimate the TE‐dependence of the 2HG and Glx signal intensity and at a TE of 120 ms in eight glioma patients to estimate the in vivo 2HG, Glx, and water T2 relaxation times.

A TE of 90 ms was found to produce a maximal 2HG integral, which was 23% larger than that at a TE of 70 ms in vivo without a significant increase in 2HG‐Glx overlap. Lipid and residual water were 26% and 16% lower, respectively, at a TE of 90 ms versus 70 ms. Fit‐quality numbers were 49% lower at a TE of 90 ms versus 70 ms, indicating enhanced fits at a TE of 90 ms. The in vivo T2 relaxation times of 2HG, Glx, and water were 264, 177, and 110 ms, respectively.

A TE of 90 ms was best with a maximal 2HG signal, minimal 2HG‐Glx overlap, and minimal residual water and lipid contamination.